Several types of agricultural harvesting vehicle include header bar assemblies. Most commonly they are encountered in combine harvesters, although variants on the basic design of header bar are also found in other harvesting vehicles such as beet harvesters, pea/bean harvesters and forage harvesters. The invention is applicable in all types of harvesting machine as are summarised above.
In, e.g., corn headers, the header bar assembly comprises a number of row units, placed side by side and each being arranged for harvesting a row of corn plants. Corn plants are typically planted in rows spaced a predetermined distance apart. Row units of corn headers are spaced a corresponding distance apart so as to be capable of following the rows while inducting the corn plants. When entering and moving through a stand of corn, the row units of the header are typically preceded by row dividers that separate the adjacent rows of plants for harvesting by the respective row units. The row units are configured and operable for receiving the stalks of the corn plants of the respective rows in succession, and removing the full or intact ears of corn, for conveying by other apparatus from the header to processing apparatus within the harvesting machine. Typically, the row units can comprise a variety of devices operable for harvesting the corn ears from the stalks, including deck plates defining a stalk receiving channel, gathering chains having teeth operable for carrying the corn ears rearward to a conveying apparatus of the header and snapping rolls located in association with the deck plates for pulling the corn stalks downwardly. In a typical configuration, the gathering chains are located above the deck plates and the snapping rolls are located below. The snapping rolls are rotatable for pulling the corn stalk downwardly, through rearward moving fingers of the gathering chains, to bring the ears to bear against the top edges of the deck plates so as to be detached from the stalks thereby. The detached ears are then carried toward the rear of the header by the gathering chains for conveying by other apparatus into the harvesting machine, while the collapsed stalks are left on the field.
In nearly all agricultural harvesting vehicles the header bar assembly is considerably wider than the body of the vehicle. This is so that the harvesting machine can harvest multiple rows of crop at a time, without the capacity of the machine being limited by the width of the vehicle body.
The width of header bar designs therefore is a significant advantage from the standpoint of harvesting efficiency, but it represents a drawback when the harvesting vehicle is required to travel on roads (as is commonly the case e.g. at the end of a working shift or when the harvester is required to move from one farm to another).
This is because the header bar assembly is significantly wider than a typical road carriageway. A harvesting machine travelling on a road with a header bar assembly extending laterally as is required during harvesting operations would be entirely impractical since the header bar assembly would foul on objects at the side of the road, and the passage of other vehicles would be impeded by the length of the header bar that extends out of the carriageway in which the harvesting machine is moving. Furthermore many narrow rural roads would be impenetrable to a harvesting machine having its header bar configured for harvesting operations.
In some corn header designs it is known for the header bar assembly to be segmented, with sections known as “wings” at each end of the header bar assembly being pivotable along a vertically extending arc to overlie a mid-section during on-road driving of the harvesting machine. Regulatory requirements in many European countries dictate that when folded up in this way the maximum width of the header bar assembly must not exceed 3.5 m. Movement of the wings to the stowed position requires their inversion.
This solution is associated with disadvantages. Primary among these is a restriction that the sum of the width of the two wings cannot be greater than the width of a fixed central section of the header bar. Otherwise, the wings would overlap each other when folded and the associated drive mechanisms may not function correctly.
Another disadvantage is the energy requirement to cause inversion of the wings as they rotate round the vertical arc. This means the harvesting machine must be fitted with a drive take-off that applies the drive normally provided for the purpose of driving moveable parts of the header bar assembly for the purpose of inverting the wings and causing them to overlie the fixed central section of the header bar.
The mass of each wing is significant. This means that the components that support them and transfer drive to them during their inversion and rotation must be robust and heavy. The power requirement for folding the wings is high, and the folding operation may be relatively slow to complete.
Publication no EP 1932416 A1 proposes a different solution to the problem of header bar width. The harvester disclosed in this document includes a segmented header bar assembly in which wings including reel segments are pivotable about vertical axes so as to protrude forwardly of a fixed central header bar section when the harvester is required to travel on roads. Motor drives are provided for rotating the wings in a horizontal arc.
Although as a result of such motion the header bar width is reduced to less than that of the harvester vehicle body, the harvester of EP 1932416 A1 appears to suffer from several disadvantages.
Among these is the fact that the wings in their folded configuration are cantilevered forwardly from the fixed header bar section. This means that the parts of the header bar and drive connections that support the wings must be particularly strong. In turn this can represent a weight disadvantage that in turn adversely affects factors such as vehicle speed, manoeuvrability and fuel consumption.
Also the header bar and the remainder of the vehicle must be carefully designed since otherwise the centre of mass of the vehicle may shift undesirably as conversion between the harvesting and driving configurations takes place. This may cause the harvester to behave in ways that are unfamiliar to an operator e.g. when driving on roads.
The arc described by the wings as they move between the folded and deployed positions is large. It is necessary for the harvester operator to clear a large area near the front of the harvester of obstructions and people before converting the machine between its two main configurations.
Once the wings are folded as noted they protrude forwardly of the central section by some distance. This means that the harvester vehicle is somewhat longer when prepared for road driving than when configured for harvesting. This is believed potentially to lead inexperienced operators to misjudge the vehicle length. Moreover in some jurisdictions vehicle regulations limit the extent to which parts of a vehicle such as a harvester protrude forwardly relative to some datum such as the cab-mounted steering wheel normally in use during road driving. It may be difficult for a vehicle designer adopting the principles described in EP 1932416 A1 to meet such requirements.